An automatic paper pickup mechanism is a very important portion of many official machines, such as printers, facsimile machines, and copying machines. The automatic paper pickup mechanism can automatically feed a stack of paper once a page into the official machine for proceeding follow-up actions, for example, printing, faxing, and copying. And, a paper pickup mechanism with a mounting shaft is a general one. In the conventional technologies, for example, an ACM (Auto Compensation Mechanism) of U.S. Pat. No. 5,527,026, the mounting shaft for picking up the paper is located at the pick-up position so as to contact with the paper, but, under this condition, if the paper is soft and slight and has less rigidity, the mounting shaft will not be urged by the paper to locate at a correct position which will always get the paper stuck. In addition, for solving the paper stuck problem described above, some other prior arts utilize a system motor to provide the power for feeding paper and additionally employ an expensive electromagnetic valve or another reserved motor for driving the mounting shaft. However, these structures cause the paper mechanism more complicated and also cost more.
It is clear that because the mounting shaft of the conventional paper pickup mechanism can not automatically move up and down, it will cause the soft and slight paper to get stuck and further bother the user. Simultaneously, if the structure of the paper pickup mechanism for moving the mounting shaft automatically becomes more complicated and the manufacturing cost increases, the competitiveness of the product will be seriously influenced. Consequently, how to move the mounting shaft automatically under a simplest mechanism for solving the paper stuck problem and reducing the cost becomes the main purpose of the present invention.